How would I open a program from a single button of another program. Help...

Experts, here's my program... It's running well now. But I just want to expand it. I want to have another program(on another frame), but I want to put the button of it on this program below to open it(when i click it). What i mean is I want to have a button that open another program, because i want to open my Cool3.java by clicking a button on the below program. Can you help me how to do that?

How to make a button specific only on a given action

Hello experts, I'm having problem still on the two buttons I made, because it has the same function, I want the other one will function as "do it button" and the other one be "open button" for the other frame... I don't know how..
heres the code

What I mean is, everytime, I enter a given number... And press the button "Solve it" nothing happen, but what does this error mean, It just pop out in the output box of net beans..

Java Code:

init:
deps-jar:
Compiling 1 source file to D:\usersfiles\JavaLibrary1\build\classes
compile-single:
run-single:
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:994)
at java.lang.Double.parseDouble(Double.java:510)
at Regression.actionPerformed(Regression.java:113)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.java:6041)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
at java.awt.Component.processEvent(Component.java:5806)
at java.awt.Container.processEvent(Container.java:2058)
at java.awt.Component.dispatchEventImpl(Component.java:4413)
at java.awt.Container.dispatchEventImpl(Container.java:2116)
at java.awt.Component.dispatchEvent(Component.java:4243)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
at java.awt.Container.dispatchEventImpl(Container.java:2102)
at java.awt.Window.dispatchEventImpl(Window.java:2440)
at java.awt.Component.dispatchEvent(Component.java:4243)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)

Read the message closely, it contains " at Regression.actionPerformed(Regression.java:113)" which is a line in your code.
It says the problem at that line is "java.lang.NumberFormatException: empty String"
Try to use that information to find out what the problem is.